Towards a scientific community consensus on designating Vulnerable Marine Ecosystems from imagery

Abstract

Management of deep-sea fisheries in areas beyond national jurisdiction by Regional Fisheries Management Organizations/Arrangements (RFMO/As) requires identification of areas with Vulnerable Marine Ecosystems (VMEs). Currently, fisheries data, including trawl and longline bycatch data, are used by many RFMO/As to inform the identification of VMEs. However, the collection of such data creates impacts and there is a need to collect non-invasive data for VME identification and monitoring purposes. Imagery data from scientific surveys satisfies this requirement, but there currently is no established framework for identifying VMEs from images. Thus, the goal of this study was to bring together a large international team to determine current VME assessment protocols and establish preliminary global consensus guidelines for identifying VMEs from images. An initial assessment showed a lack of consistency among RFMO/A regions regarding what is considered a VME indicator taxon, and hence variability in how VMEs might be defined. In certain cases, experts agreed that a VME could be identified from a single image, most often in areas of scleractinian reefs, dense octocoral gardens, multiple VME species' co-occurrence, and chemosynthetic ecosystems. A decision flow chart is presented that gives practical interpretation of the FAO criteria for single images. To further evaluate steps of the flow chart related to density, data were compiled to assess whether scientists perceived similar density thresholds across regions. The range of observed densities and the density values considered to be VMEs varied considerably by taxon, but in many cases, there was a statistical difference in what experts considered to be a VME compared to images not considered a VME. Further work is required to develop an areal extent index, to include a measure of confidence, and to increase our understanding of what levels of density and diversity correspond to key ecosystem functions for VME indicator taxa. Based on our results, the following recommendations are made: 1. There is a need to establish a global consensus on which taxa are VME indicators. 2. RFMO/As should consider adopting guidelines that use imagery surveys as an alternative (or complement) to using bycatch and trawl surveys for designating VMEs. 3. Imagery surveys should also be included in Impact Assessments. And 4. All industries that impact the seafloor, not just fisheries, should use imagery surveys to detect and identify VMEs.

Keywords: Areas beyond national jurisdiction; Deep-Sea imagery; Significant adverse impacts; VME indicator taxa; Vulnerable marine ecosystems.

Figure 1. Examples of images that could be illustrative of significant adverse impacts (SAIs).

(A) Barren seafloor on Yuryaku Seamount in the Emperor Seamount Chain showing multiple scars from bottom contact gear (Baco, Morgan & Roark, 2020, CC BY-NC-ND 4.0). (B) Sponge rubble from Learmonth bank, a granite knoll lying in EEZ waters of the border between Canada and Alaska (north of Haida Gwaii). The pile of dead glass sponges (family: Rossellidae) were (likely) detached/crushed from fishing gear, rolled around on the seafloor (which creates that distinct potato shape), and then accumulated against the base of Learmonth Bank because of the circulation patterns in Dixon Entrance. Image: Chu (2010) (C) lost fishing line at a Costa Rica methane seep (~1,000 m). Image: Schmidt Ocean Institute. FK190106, E. Cordes Chief Scientist. (D) A discarded trawl net and floats hooked on the seabed of a seamount off New Zealand at 900 m depth Image: NIWA. (E) Marks from demersal trawling over soft sediment habitats (~1,000 m depth) off Greenland (Long et al., 2021). (F) With an average set length of 3 km, derelict bottom longlines on Northeast Pacific Seamounts are extensive and fairly mobile, entangling and destroying biological structures while scouring the seafloor (Dellwood South Seamount). Image: Ocean Exploration Trust/Northeast Pacific Seamount Expedition Partners, J. Pegg (Fisheries and Oceans Canada). © His Majesty the King in Right of Canada, 2023 (G) image of lost fishing gear entangled in deep-sea corals on Southeast Hancock Seamount in the Northwestern Hawaiian Islands. Image: A. Baco FSU, and E.B. Roark TAMU, NSF, with HURL Pilots T. Kerby and M. Cremer. (H) Dead Widow Rockfish in a lost gill net on the summit of Cobb Seamount. Image: Curtis et al. (2015) /Fisheries and Oceans Canada. © His Majesty the King in Right of Canada, 2023.

Figure 2. Examples of deep-sea scleractinian reefs that can be identified as a VME from a single image.

(A) Solenosmilia variabilis Duncan, 1873 reef with associated rockfish and invertebrates on Colahan Seamount on the Northwestern Hawaiian Ridge (Baco, Morgan & Roark, 2020, CC BY-NC-ND 4.0). (B) A thicket of the reef-forming stony coral Solenosmilia variabilis at 1,140 m depth on seamount z16, Southern Tasmania, Australia. Image: CSIRO, Survey SS200611. (C) A Desmophyllum pertusum (formerly Lophelia pertusa (Linnaeus, 1758)) reef on Anton Dohrn Seamount west of Scotland. Image: NERC funded Deep Links Project-Plymouth University, Oxford University, BGS, JNCC. (D) A thicket of the reef-forming stony coral Solenosmilia variabilis at 1,000 m depth on the summit of a small seamount off New Zealand; brisingid seastars, small crinoids, and fluffy octocorals are also present. Image: NIWA. (E) Cold-water corals Desmophyllum pertusum and Madrepora oculata Linnaeus, 1758, with brisingidae within Explorer Canyon, North East Atlantic. Image: JC125 cruise, National Oceanography Centre, Southampton. (F) A Desmophyllum pertusum reef at ~200 m in the fjords of the Central Coast of British Columbia, Canada. Image: Fisheries and Oceans Canada. © His Majesty the King in Right of Canada, 2023.

Figure 3. Examples of coral gardens that can be identified as a VME from a single image.

(A) An octocoral and antipatharian garden on Koko Seamount in the Emperor Seamount Chain (Baco, Morgan & Roark, 2020, CC BY-NC-ND 4.0). (B) Extensive Parastenella spp. octocoral gardens encircle the slopes of the Dellwood Seamounts, in the Canadian Northeast Pacific. Image: Ocean Exploration Trust/Northeast Pacific Seamount Expedition Partners, D. Fornari (WHOI-MISO Facility). © His Majesty the King in Right of Canada, 2023. (C) A forest of red and white tree corals (dominated by Primnoa pacifica Kinoshita, 1907) on the plateau break of SGaan Kinghlas-Bowie Seamount (~600 m depth), one of the tallest seamounts in the Northeast Pacific and Canada’s shallowest underwater volcano. Also visible are some of the rougheye rockfish (Sebastes aleutianus (Jordan & Evermann, 1898)) hiding between the 1–2 m stands. Image: Ocean Exploration Trust/Northeast Pacific Seamount Expedition Partners, D. Fornari (WHOI-MISO Facility). © His Majesty the King in Right of Canada, 2023. (D) Cold-water coral garden within the Menez Gwen protected area at the Azores Marine Park. Image: Missão Seahma, 2002 (FCT, Portugal PDCTM 1999MAR15281). (E) A mixed VME of primnoid corals and sponges on a seamount south of New Zealand on the Macquarie Ridge. Image: NIWA. (F) An octocoral garden on O’Brian Seamount in the North Pacific. Image: A. Baco FSU, E.B. Roark and K. Shamberger TAMU, NSF, and the ROV JASON II.

Figure 4. Example images of sponge aggregations that were considered a VME from a single image.

(A) A deep-sea sponge aggregation, comprising Geodia sp., from the Faroe Shetland Channel in UK waters. Image: JNCC and Marine Scotland Science survey 1517S. (B) Sponge ground, formed by the bird’s nest sponge Pheronema carpenteri (Thomson, 1869), at the flank of Pico Island in the Azores (800 m). Image: Rebikoff Foundation. (C) A city of glass sponges covers the summit of Explorer Seamount, a supervolcano in the Northeast Pacific and Canada’s largest underwater volcano. This new species of Pinulasma dominates otherwise relatively bare and exposed lava at 800 m depth, adding vertical relief and complex structure to the terrain. Image: Ocean Exploration Trust/Northeast Pacific Seamount Expedition Partners, D. Fornari (WHOI-MISO Facility). © His Majesty the King in Right of Canada, 2023. (D) Sponge and bryozoa/hydroid community at 85 m depth off Jurien Bay, Western Australia. Image: CSIRO, ‘Voyage of Discovery’ Survey SS200507.

Figure 5. Example images of chemosynthetic ecosystems that can be identified as a VME from a single image.

(A) Stalked barnacles completely covering rocks near a hydrothermal vent on the Kermadec Volcanic Arc north of New Zealand. Image: NOAA, NIWA, GNS. (B) Methane seep mussel and tubeworm community with associated epifauna near Trinidad and Tobago. Image: Ocean Exploration Trust, EV Nautilus cruise NA054. (C) Hydrothermal vent chimney with the endemic vent mussel Bathymodiolus azoricus von Cosel, Comtet & Krylova, 1999 (Threatened species; Thomas et al., 2021) at the Lucky Strike protected area at the Azores Marine Park. Image: © Missão Seahma, 2002 (FCT, Portugal PDCTM 1999MAR15281). (D) Hydrothermal vent covered in a chemosynthetic community of provannid snails Alviniconcha spp. and Ifremeria nautilei, and the mussel Bathymodiolus septemdierum Hashimoto & Okutani, 1994 with associated invertebrates from the Lau Basin hydrothermal vents, in the Kingdom of Tonga (Threatened species; Thomas et al., 2021). Image: SOI, ROPOS, Du Preez. (E) A low flow hydrothermal vent chimney covered in chemosynthetic white bacterial mats and clumps of endosymbiont containing tubeworms (Ridgeia piscesae Jones, 1985) from Endeavour Hydrothermal Vent MPA, Canada. Image: Fisheries and Oceans Canada. © His Majesty the King in Right of Canada, 2023. (F) Zoomed-in image of a clump of sulfide worms (Paralvinella sulfincola Desbruyères & Laubier, 1993)—a pioneer species that facilitates colonization by the limpets (Lepetodrilus fucensis J. H. McLean, 1988) and other vent associated animals. High flow site at Endeavour Hydrothermal Vent MPA, Canada. Image: Fisheries and Oceans Canada. © His Majesty the King in Right of Canada, 2023.

Figure 6. Examples of soft-sediment communities that can be considered VMEs from a single image.

(A) A Syringammina fragilissima Brady, 1883 xenophyophore aggregation at the Darwin Mounds Marine Protected Area northwest of Scotland. Image: National Oceanography Centre, UK (B) mixed sea pens and an Acanella arbuscula bamboo coral on the continental slope west of Ireland. Image: the SeaRover project, co-funded by the Irish Government and the European Maritime and Fisheries Fund 2014–2020. (C) Pheronema carpenterii Thomson, 1869 sponge aggregation in the Porcupine Seabight southwest of Ireland. Image: University of Plymouth, Marine Institute Ireland, Eurofleets 2. (D) Radicipes gracilis meadow at 667 m near Bear Island, Norway. Image: Mareano programme, Institute of Marine Research, Norway, cruise 2009105.

Figure 7. Examples of VME Indicators acting as nurseries.

(A) Bathypathes (black coral) as nursery habitat for juvenile galatheid crabs. Costa Rica margin Las Gemmelas seamount. Image: RV Falkor/SuBastian FK190106 Dive S0225; Schmidt Ocean Institute, CC-BY-NC-SA 3.0. (B) Egg capsules of the deep-water catshark Galeus melastomus Rafinesque, 1810 in a tubeworm field (Lamellibrachia spp.) at the North Alex Mud Volcano, eastern Mediterranean Sea. Image: T. Treude (C) Xenophyophore on the Costa Rica Margin. Image: Schmidt Ocean Institute. (D) Fish eggs attached to Reticulammina sp. test, identified as Paraliparis sp. via DNA analysis (GenBank MN509401); eggs were dead upon discovery, after having been in shipboard incubation experiments for 10 days. (E) Closer view of fish eggs from (D). Image for (D and E): Levin & Rouse (2019). Photographs by Greg Rouse.

Figure 8. Example images of VMEs that were harder to distinguish from a single image.

(A) A large antipatharian with associated galathaeid crabs from the Northwestern Hawaiian Ridge. Image: A. Baco FSU, E.B. Roark TAMU, NSF, with HURL Pilots T. Kerby and M. Cremer. (B) Low-density fields of stalked glass sponges (genus Hyalonema) at 650 m depth, extending over ~80% of the 2 km long video transect off Ningaloo Western Australia. Image: CSIRO, ‘Voyage of Discovery’ Survey SS200507.

Figure 9. Flow chart for determining whether the faunal community in a single frame or image represents a VME.

If a “Yes” is obtained in any step, the image can be considered a VME and no further steps need to be tested. A more in–depth explanation of each box along with explanations of the associated FAO criteria can be found in the text under Question 3.

Figure 10. Locations of imagery data used for Question 4 (labelled points) and RFMO/As (colored regions) evaluated in this study.

SIOFA, Southern Indian Ocean fisheries agreement region; SPRFMO, South Pacific regional fisheries management organisation; NPFC, North Pacific fisheries commission; WECAFC, Western Central Atlantic fishery commission; CECAF, fishery committee for the Eastern Central Atlantic; NAFO, North Atlantic fisheries organisation; NEAFC, North East Atlantic fisheries commission; SEAFO, South East Atlantic fisheries organisation; GFCM, general fisheries commission for the mediterranean; CCAMLR, commission for the conservation of antarctic marine living resources.

Figure 11. Boxplots of YMN (Yes, Maybe, No) from images examined for VMEs.

(A)Number of Taxa per Image, (B) Density of Alcyonacea, (C) Density of Scleractinia, (D) Density of Porifera, and (E) Overall Density. Global one-way ANOVA results are provided below each figure. Figures for additional taxa are available in Fig. S1.